Objectives: Licensure of acellular pertussis vaccines awaits the evaluation of several recently completed and ongoing efficacy trials. Results of these trials are dependent upon the laboratory procedures employed to diagnose Bordetella pertussis infection. Similarly, long-term surveillance of the pertussis immunization program requires the development and implementation of sensitive and specific diagnostic procedures. Licensure of less reactogenic acellular pertussis vaccines will provide an opportunity to immunize older age groups, however, data on pertussis morbidity in adults and the role of adults and adolescents in transmission are needed to make appropriate decisions on expanded use of these vaccines. To increase knowledge of pertussis diagnosis and epidemiology, the Laboratory has initiated projects: a) To develop and improve laboratory procedures to diagnose infection with Bordetella pertussis. b) To determine which diagnostic procedures have the highest sensitivity and specificity for pertussis diagnosis at the different stages of illness. c) To apply these techniques to understand epidemiology of pertussis. FY95 Activities: 1. Continued a collaborative study with US Navy to determine the prevalence of B. pertussis infection in Marine recruits. Infection was evaluated by culture, serology and by polymerase chain reaction (PCR) technology. From October 1993 through July 1994 samples were collected on recruits reporting to sick call with 7 or more days of cough. Sample collection and culture was performed by the Navy medical staff on 156 subjects and a total of about 3200 ELISA tests (about 1800 in FY95) were performed by the Laboratory of Pertussis. No subjects were positive by culture, however, depending on definition, 2 to 5% of subjects met a serological case definition for pertussis. Final assay optimization and validation of the PCR assay was completed and about 180 tests were performed on nasopharyngeal samples from the Navy study. 2. Participated in organizing and conducting a CDC-hosted consensus conference on the use of pertussis serologic assays in evaluating the epidemiology of pertussis in the US.